Evaporator



March 23, 1954 A, CROSS 2,672,926

' EVAPORATOR Original Filed Sept. 9, 1946 3 Sheets-Sheet 1 In 1 e rz .755 epfi f2.

J. A. CROSS March 23, 1954 EVAPORATOR 3 Sheets-Sheet 2 Original Filed Sept. 9

March 23, 1954 J. A. CROSS 2,672,926

EVAPORATOR Original Filed Sept. 9, 1946 3 Sheets-Sheet I5 w 5 1 I 1 m 7 12 5 f I i z E i i 5 A 1 I 1 I i 9 I. JZ i J7Z7/7Zf0fi- Z2 (7556 05 12 61"055.

tom of each sump a pipe 2! leading to a pump 22, each pump being preferably driven by an electric motor and delivering its output to a riser pipe 6, which as noted before delivers the liquor into the chamber 5 at the top of each tube chest.

The fresh dilute liquor to be evaporated will be introduced through a pipe 23 into the downfiow pipe 2| of the first evaporator unit whereits recirculation and subjection to evaporation in the third unit may be caused to attain the final desired density. The rate of withdrawal of liquor through the draw-01f pipe will be maintained at such a rate as to make certain that liquor of the desired density only. is withdrawn...

' vIt is clear that a large number or ;a small number of identical units may be connected in series, as described, in order to obtain a desired concentration under eificient operating conditions.

, As stated hereinbefore, the present invention is especially suitable for evaporation of liquors at low temperatures such as are made possible by evaporation under vacuum. In such case,

suitable equipment is connected with the vapor it will be drawn through the pump 22 and thence delivered upwardly through the riser pipe 6'into--- the top of the first evaporator chamber 5-. It is contemplated that some of the liquor will recirculate through the first evaporator unit many times as the vapor is being extracted from it in the falling film tubes.

A draw-off pump 24 connected with the drawofi pipe 25 maintains a continuous discharge of concentrated liquor from the last evaporator. Between the first and second units, that is, connected with their sumps, is a pipe 26 and between the sump of the second unit and the sump of the The operation of i.

third unit is another pipe 21. the draw-ofi pump and the feed of fresh liquor through the pipe 23 will therefore induce a continuous flow of liquor from the first unit to the second and from the second to the third and from the third to the draw-off pump or to such i other units as may be connected between that point and the draw-off pump.

While three connected units are shown in the evaporator herein described, it is contemplated the number of units required for the most efiicient operation on'any proposed installation.

The operation lows:

Fresh liquor is supplied through a pipe 23 to the down-flow pipe leading to the pump con nected with the first unit. This liquor along with other liquor already in thesystem is delivered to the top of the'first unit and under the controlling effect of the static head and the tubes 1 will cause a film of the liquor to flow downwardly along the entireinside of'each of the tubes in the first unit. While liquor is being recirculated through the falling film unit the vapor released from the films flows from the lower ends of the tubes into the vapor separation drum. The circular motion imparted to the vapor will cause entrained droplets to sweep along the walls of the drum andfall back into the sump of each i drum while the vapor, free from droplets, may

be'evacuated through the vapor outlet pipe H3.

The rate of evaporation will be highest in the first unit and lowest in the last evaporator unit.

of the device, briefly, is as fol- As a, result the second unit will'beoperating on 1 a liquor of considerably higher-density than the fresh liquor introduced into the first unit. The liquor flowing from the second unit, to the third outlet pipe l8,that is, such as pumps or condensers or both, 'to' maintain as high a degree of vacuum in the vapor space within the drums and within the tubes as may be desired.

Obviously, the means for evacuating the vapors will be suited to whatever vapor pressures, positive or vacuum, prevail in the system. Variable speed pumps, valves, or other devices may be employed formaintaining uniform or providing variable operating conditions.

While I have shown and described'herein, for illustrative purposes, a preferred embodiment of the invention, it should be understood that considerable variation in the details of construction may be employed without departing from the spirit and scope of the invention, as defined in the following claims.

I claim as my invention:

1. An evaporator comprising a vertical tube chest having vertical tubes and top and bottom plates retaining said tubes, an inlet port for admission of heating fluid into the space surrounding the tubes and an outlet portfor said fluid, a centrifugal vapor separator having a horizontal axis and positioned and connected with the bottom of said tube chest to receive liquid solution and vapor from the bottom ends of the tubes tangentially into said separator, said separator having a vapor outlet concentric With said axis and a liquid outlet eccentric to said axis, an upper chamber at the top of said tube chest with which the chest tubes communicate, open ended film feed control tubes extending concentrically downwardly into said chest tubes and upwardly into said upper chamber, means for recirculating liquid solution from said vapor separator liquid outlet into said upper chamber forfilm flow downwardly past the film feed tubes through said chest tubes, said upper chamber having an outlet for vapor only through said control and chest tubes into said separator, means for introducing a solution to be concentrated into said evaporator for flow through said chest tubes and means for. withdrawing concentrated solution from said evaporator.

2. An evaporator comprising a series of vertical tube chests, each chest having vertical tubes and top and bottom plates retaining said tubes, an inlet port for admission of heating fluid into the space surrounding the tubes and an outlet port for said fluid, a centrifugal vapor separator having a horizontal axis and positioned and connected with the bottom of said tube chest to receive liquid solution and vapor from the bottom ends of the tubes tangentially into'said separator, said separator having a vapor outlet concentric with said axis and a liquid outlet eccentric to said axis, an upper chamber at the top of said 114 w a an e e i ee d e r'end-d r n 5 iele w i ei w th. ea he -t tube commune cate, open ended film feed control tubes extending concentrically downwardly into said chest tubes and upwardly into said upper chamber, means for recirculating liquid solution from said vapor separator liquid outlet into said upper chamber for film fiow downwardly past the film feed tubes through said chest tubes, said upper chamber having an outlet for vapor only through said control and chest tubes into said separator, means for continuously introducing into the first chest of said series a solution to be concentrated by fiow through the chest tubes, means for continuously advancing partially concentrated solution from the first chest to the second chest and in like manner to subsequent chests in the series for similar recirculating and concentration in each chest and means for continuously withdrawing solution at a desired concentration from the last chest of the series.

3. An evaporator comprising a series of vertical tube chests, each chest having vertical tubes and top and bottom plates retaining said tubes, an inlet port for admission of heating fiuid into the space surrounding the tubes and an outlet port for said fluid, a centrifugal vapor separator having a horizontal axis and positioned and connected with the bottom of said tube chest to receive liquid solution and vapor from the bottom ends of the tubes tangentially into said separator, said separator having a vapor outlet concentric with said axis and a liquid outlet eccentric to said axis, an upper chamber at the top of said tube chest with which the chest tubes communicate, open ended film feed control tubes extending concentrically downwardly into said chest tubes and upwardly into said upper chamber, means for recirculating liquid solution from said vapor separator liquid outlet into said upper chamber for film fiow downwardly past the film feed tubes through said chest tubes, said upper chamber having an outlet for vapor only through said control and chest tubes into said separator, the separators associated with the several chests being axially aligned providing a common vapor passage through them concentric with their vapor outlets, means for continuously introducing into the first chest of said series a solution to be concentrated by fiow through the chest tubes, means for continuously advancing partially concentrated solution from the first chest to the second chest and in like manner to subsequent chests in the series for similar recirculating and concentration in each chest and means for continuously withdrawing solution at a desired concentration from the last chest of the series.

JOSEPH A. CROSS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 341,669 Lillie May 11, 1886 378,843 Lillie Feb. 28, 1888 484,831 Stillman Oct. 25, 1892 965,388 Kestner July 26, 1910 1,323,013 Christie Nov. 25, 1919 1,717,927 Hughes et a1 June 18, 1929 2,168,362 Peebles et al. Aug. 8, 1939 

